From b597c318b86b5ad2bca1f72ee8c0fbe33cbb7dad Mon Sep 17 00:00:00 2001 From: Yao Qi Date: Sun, 28 Dec 2014 16:12:53 +0800 Subject: [PATCH] always read synthetic pointers as signed integers I see the error message "access outside bounds of object referenced via synthetic pointer" in the two fails below of mips gdb testing print d[-2]^M access outside bounds of object referenced via synthetic pointer^M (gdb) FAIL: gdb.dwarf2/implptrconst.exp: print d[-2] (gdb) print/d p[-1]^M access outside bounds of object referenced via synthetic pointer^M (gdb) FAIL: gdb.dwarf2/implptrpiece.exp: print/d p[-1] in the first test, 'd[-2]' is processed by GDB as '* (&d[-2])'. 'd' is a synthetic pointer, so its value is zero, the address of 'd[-2]' is -2. In dwarf2loc.c:indirect_pieced_value, /* This is an offset requested by GDB, such as value subscripts. However, due to how synthetic pointers are implemented, this is always presented to us as a pointer type. This means we have to sign-extend it manually as appropriate. */ byte_offset = value_as_address (value); if (TYPE_LENGTH (value_type (value)) < sizeof (LONGEST)) byte_offset = gdb_sign_extend (byte_offset, 8 * TYPE_LENGTH (value_type (value))); byte_offset += piece->v.ptr.offset; We know that the value is really an offset instead of address, so the fix is to extract the value as an (signed) offset. gdb: 2015-01-08 Pedro Alves Yao Qi * dwarf2loc.c (indirect_pieced_value): Don't call gdb_sign_extend. Call extract_signed_integer instead. * utils.c (gdb_sign_extend): Remove. * utils.h (gdb_sign_extend): Remove declaration. --- gdb/ChangeLog | 8 ++++++++ gdb/dwarf2loc.c | 16 +++++++++++----- gdb/utils.c | 17 ----------------- gdb/utils.h | 5 ----- 4 files changed, 19 insertions(+), 27 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 2fa7422..fea9207 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2015-01-08 Pedro Alves + Yao Qi + + * dwarf2loc.c (indirect_pieced_value): Don't call + gdb_sign_extend. Call extract_signed_integer instead. + * utils.c (gdb_sign_extend): Remove. + * utils.h (gdb_sign_extend): Remove declaration. + 2015-01-07 Pierre Muller PR symtab/17811 diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c index 2bd12d6..bdb2160 100644 --- a/gdb/dwarf2loc.c +++ b/gdb/dwarf2loc.c @@ -2012,6 +2012,7 @@ indirect_pieced_value (struct value *value) int i, bit_offset, bit_length; struct dwarf_expr_piece *piece = NULL; LONGEST byte_offset; + enum bfd_endian byte_order; type = check_typedef (value_type (value)); if (TYPE_CODE (type) != TYPE_CODE_PTR) @@ -2056,11 +2057,16 @@ indirect_pieced_value (struct value *value) /* This is an offset requested by GDB, such as value subscripts. However, due to how synthetic pointers are implemented, this is always presented to us as a pointer type. This means we have to - sign-extend it manually as appropriate. */ - byte_offset = value_as_address (value); - if (TYPE_LENGTH (value_type (value)) < sizeof (LONGEST)) - byte_offset = gdb_sign_extend (byte_offset, - 8 * TYPE_LENGTH (value_type (value))); + sign-extend it manually as appropriate. Use raw + extract_signed_integer directly rather than value_as_address and + sign extend afterwards on architectures that would need it + (mostly everywhere except MIPS, which has signed addresses) as + the later would go through gdbarch_pointer_to_address and thus + return a CORE_ADDR with high bits set on architectures that + encode address spaces and other things in CORE_ADDR. */ + byte_order = gdbarch_byte_order (get_frame_arch (frame)); + byte_offset = extract_signed_integer (value_contents (value), + TYPE_LENGTH (type), byte_order); byte_offset += piece->v.ptr.offset; gdb_assert (piece); diff --git a/gdb/utils.c b/gdb/utils.c index 084db87..72b1e2a 100644 --- a/gdb/utils.c +++ b/gdb/utils.c @@ -3021,23 +3021,6 @@ align_down (ULONGEST v, int n) return (v & -n); } -/* See utils.h. */ - -LONGEST -gdb_sign_extend (LONGEST value, int bit) -{ - gdb_assert (bit >= 1 && bit <= 8 * sizeof (LONGEST)); - - if (((value >> (bit - 1)) & 1) != 0) - { - LONGEST signbit = ((LONGEST) 1) << (bit - 1); - - value = (value ^ signbit) - signbit; - } - - return value; -} - /* Allocation function for the libiberty hash table which uses an obstack. The obstack is passed as DATA. */ diff --git a/gdb/utils.h b/gdb/utils.h index 0a73864..3debde7 100644 --- a/gdb/utils.h +++ b/gdb/utils.h @@ -340,11 +340,6 @@ extern int myread (int, char *, int); extern ULONGEST align_up (ULONGEST v, int n); extern ULONGEST align_down (ULONGEST v, int n); -/* Sign extend VALUE. BIT is the (1-based) index of the bit in VALUE - to sign-extend. */ - -extern LONGEST gdb_sign_extend (LONGEST value, int bit); - /* Resource limits used by getrlimit and setrlimit. */ enum resource_limit_kind -- 2.7.4